949 IS I No . K\ Jl 1 I I it \m l/V //V7 At / v limber For Structural Purpose Ami Announcement 'I he >ffe J Timhi Leg mate Place Kd licit At Timber Supply at Rea* m le »t Modern Structural Re rt len Pi Tooa eticc and D I 1 Mill < true o D he tire i xard I ire Rt irdents Wood Preeerva igH \ i IO \L LIBBER v Rf as o r io (TENS! Of A R IIC • 9 • • ♦ • • • ' » * • • • ** Timber For Structural Purposes by E. A. STERLING ' £DUCAT/oVj TRADE E DEPAR1 XTEN5ION UM ENT ECONOMY - STABILITY SERVICE Published by the National Lumber Manufacturers Association Trade Extension Department Chicago, Illinois January, 1916 Engineering Bulletin No. 1 January. 1916 ri \ Timber for Structural Purposes By E. A. Sterling Announcement The National Lumber Manufacturers As- sociation, through its Trade Extension De- partment, is preparing a series of engineering publications on structural timber. The word "timber," in this case, is inter- preted in its broadest application to all wood products used in construction. These bulletins will be available to all who are interested in standard and economical wood construction. The possibilities and advantages of lumber in modern structures, as well as its limitations, will be fully and frankly outlined, and reliable information as to strength, durability, and other characteristics, presented. Supplementing the information on the qualities of timber as a building material, details of proper design, working drawings, new developments, and similar data will be published. Modern wood construction in its many en- gineering phases will he presented on its own merits, with prej- udice towards no other building material. Many materials are embodied in the best designed structures, each with individ- ual merits and special fitness for the purpose. Service for Where wood products are better or as good, Architects, or by proper treatment can be made equal to Engineers and any other material, it is the legitimate desire Builders of the lumber industry that their selection and use shall be given full consideration. The policy will be to present engineering data relating to timber as a structural material, and in a spirit of helpful service to advocate the use of wood in construction wherever it fully meets all requirements of safety and economy. The informa- ^ tion the manufacturers are ready to give should result in inu- CT tual benefit, since the thoughtful intelligent use of structural f? Page thrre TIMBER FOR timber will assure the erection of buildings embodying strength, symmetry, fire-resisting qualities and permanence to an extent which will reflect credit on both the material, the designers and the builders, and be looked upon favorably by insurance companies and the compilers of building ordinances. The service proposed goes farther than dissemination of informa- tion, because back of the whole movement is Association effort which aims to furnish structural timber which is standard as to size and quality, classified definitely by grading rules, and in the case of some of the more important species, trademarked as a guarantee of grade and quality. Engineering Timber is one of the most essential and widely Data used materials of construction. Modern engi- neering practice and the highest development of architectural skill find use for structural timber of many kinds in a wide variety of structures. \Vhil< many other excellent building materials have come into mm for purposes to which they are particularly adapted, timber retains the inherent advantage of economy, permanence, strength and safety. Knowledge of the material, coupled with its wise use . underlie the attainment of these service requirements with an\ building material. Since timber for many purposes is the most idap table and the must available of any material, it is impor- tant that its possibilities and advantages, as well as its limita- tions, m standard construction, should be mon generally k» IO\\ ii Frank recognition is given to the fact that engineering and scientific study has not bt « n as fully developed with structural timber as w ith some other materials, nor have the Available facts as to the strength and other physical ehararli risticfl of woods been given as wide appli< tion in construction work as the im- portance of the material justifi The comparath e absena of thes4 engineering data is. however, a condition of the past rather than tin pi tit. Tin United States J < st Products Laboratory, sonu of th< railroad testing departments, and a /'> _' "U STRl ( 'TV HAL PURPOSES number of educational institutions have been accumulating data for many years. While some of the invest iff at ions were not in accordance with the comprehensive plan which would lead to uniformly definite results, sufficient facts arc at hand to meet all practical requirements. Timber's The fundamentals in the proper and satisfac- Legitimate tory use of structural timber arc that the kind Place and grade should la- properly selected to meet specific service requirements; that the members should be incorporated in the structure in accordance with the best engineering and architectural knowledge of safe and p< i nianent design; and where not suitable for a particular use in its natural state, that the timber should be treated to prei en1 deca) or retard fire and thus adapted to the requirements of th< structure. Anv building material mai fail or become a menaci to human life and property if improperly used. The lumber industiN knows that its material is safe and economical when properly used. It does not want lumber used under any other condit ion. Educational Structural timber and wood products generall) Publicity have not been extensively advertised, h cause of the assumption that their merits were already known. As a matter of fact, wood has been such a c immon n ml;i\ article that the universal familiarity with it has h d to a very general rather than specific knowledge of its quali ti< a and uses. More definite information is t<> be disseminated, not because the average engineer, builder or carpenter d< s not knew the general value of wood for construction purposes, hut for the reason that the last use and the safe si im come from more intimate knowledge of kinds and grades <»!' timber in r< hi tion to the place they are to be used. The strength char act* r- istics, resistance to decay, and possibilities of treatment t nlapt non-durable or cheaper grades to proper condition of sen are neglected subjects. Si no wood is a natural prod- >' - TIMBER FOR uct and is not manufactured in accordance with specifications and methods which give certain uniform results in the finished product, it follows that general knowledge of lumber should be supplemented by the results of technical investigations as to the character and quality of different woods, under varying conditions of growth and service. Available Good lumber is just as obtainable, possesses the Supply s ame structural characteristics, and is as safe and economical today as it ever was. In fact, with the development of transportation facilities and the better class- ification of kinds and grades, timber is more generally available and the quality better adapted to varying requirements than twenty years ago. Supplementing these advantages, are the recent data on physical characteristics, and the development of wood-preserving and fire- retarding materials and processes. Tlie Tnited States Government estimates conservatively place the amount of merchantable standing timber in the United States at over 2800 billion feet. This is slightly more than half of the original stand, the difference representing what lias been utilized for general consumption, what has been cleared from agricultural lands and what has been destroyed by forest fires and waste. Dining the past fifty years there has been a natural shifting in the sources of lumber production, with a less marked change in the centers of consumption. In- dustrial development has moved gradually westward and southward, following to an extent the opening up of new for* st regions as railroad facilities were extended. In some of the earlier regions of greatest lumber production the supply has lx i n greatly reduced, although local requirements are still sup- plied, except in huge dimension timbers which have to come from the more distant points. Hut nowhere, even in the tree- less regions, is there any difficulty in obtaining structural timber or wood products of kind and quality to meet all needs. Most of the present availabl- standing timber is in fi\ I gi'< at forest regions, namely, the Northern. Central. Southern, Rocky J } a <j ( STRUCTURAL PURPOSES Mountain and Pacific, with fully half the reserve supply in the Pacific Northwest. Rail transportation links each of these with the points of demand. Agricultural and industrial devel- opments have made the great central states and the middle tier eastward to the Atlantic the largest consuming centers. Water transportation now brings the enormous timber supply of the Pacific Coast closer to the larger centers of population in the East; while the cheaper water rates also result in a large move- ment of lumber from the Gulf ports and the south Atlantic states to the distributing cities in the Northeast. The present merchantable supply of timber will last nearly sixty years at the present rate of cutting. This, however, by no means indicates that the supply will be exhausted at the end of that period nor that exorbitant prices will ultimately prevail. The protection being given to forests against destruction by rire, the lower per capita consumption, the use of timber more wisely and by treatment or selection assuring longer life in service, the adoption of more intensive and less wasteful log- ging methods, the utilization of non-agricultural lands for for- est production, and the annual growth throughout the enor- mous forest area will, before a period of exhaustion is at hand, bring the nation's annual wood production up to an amount approximating the consumption, and secure an adequate sup- ply for an indefinite period. Messrs. W. B. Greeley and II. S. Betts, of the U. S. Forest Service, in a paper presented at the International Engineering Congress in San Francisco September, 1915, state as follows: "With its enormous areas of non-agricultural lands, appait ntly best suited to the production of timber, in the natural order of tilings, it is prob- able that the United States will not only supply its own needs but continue to be a large exporter of timber. Even the quality of the lumber placed upon the market, which is of primary interest to the structural engineer, will chance hut verv gradually as old sources of supply renew their stands of merchantable material. For the next thirty or forty years at least, there is no question as to the ability of the United States to furnish high-grade structural timbers from its southern pine and Douglas fir forests, to meet almost anv demand for such material from any portion of the world." Page seven TIMBER FOR As a further indication that lumber of all kinds is available for all purposes, the following estimate of annual production is quoted from "Lumber and Its Uses," by R. S. Kellogg: Lumber Production in the United States. Million Species Bd. Ft. Most Largely Produced in Yellow pine 16,000 ha.. Miss., Tex., X. C, Ala., Ark., Va., Douglas fir 6,000 Wash., Ore., Calif. Oak 4,400 W. Va., Tciin.. Ky.. Va., Ark., Ohio Northern pine 3,000 Minn.. Wi>.. Me.. N. H., Mich. Eastern hemlock 2.500 Wis., Mich., Pa.. W. Va. Western jrellovi pine 1.400 Calif ., Idaho, Wash., Ore. Maple 1.200 Mich., Wis., Pa., N. Y. Eastern spruce 1,100 Me., W. Va., N. H., Vt. < iypress 1,100 La.. Fla., Ga.. Ark. Yellow poplar 800 W. Va.. Tenn., Ky.. Va., X. C. lied gum . &00 Ark.. Miss., Tenn., La. Ch.-tnut G50 W. Va., Pa., Va., Conn., N. C. Redw ood 525 ( alifornia Beech 475 Midi.. Ind.. Pa., Ohio, X. Y., W. Va. Birch 425 Wis.. Midi.. Me.. Vt., X. Y. We rn white pine 400 Idaho. Wash., Mont. Basswood 3T5 Wis., Midi., W. Va., X. \ . ( !< .1 ton wood 350 Miss., Ark., La.. Mo. Elm 325 Mich., Wis., Ohio, Ind., Mo. Western larch 300 Mont., Idaho, Wash. Western >pruce 300 Wash., Ore., Colo. Western hemlock 300 Wash., Ore., Idaho Hickory 300 Ark.. Tenn.. Kv.. Ohio, Inch Ash .' . 275 Ohio. Ark., Ind., Tenn., Wis. Western cedar 250 Wash., Idaho, Ore., Cal. White fir 140 Cal., Ore., Idaho Sugar pine 140 California Tupelo 140 La., X. C, Ala., Va. Tamarack 125 Minn.. Wis., Mich. Eastern cedar 125 Tenn., Va,, Mich., Ala. Balsam fir 100 Me., Minn., Vt., Mich. Sycamore 55 Mo., Ind., Ark., Tenn. Walnut 45 Ohio, Ind.. Kv., 111., Mo. Cherry 25 W. Va.. Pa., N. Y., Ohio Buckeye 25 Tenn., W. Va., X. C. Ky. Willow . . 20 Mississippi Noble fir 17 Oregon Magnolia 10 Louisiana Other species 38 Total 44,550 Page eight Fla., STRUCTURAL PURPOSES The annual average wood consumption, excluding firewood and rails', in the l r nited States for the past few years has been about V2 billion feet B. M. Of this amount some 40 biilion feet is in the form of manufactured lumber. The percentage of this total used for construction purposes has not been deter- mined accurately, the best figures indicating that about 20 per cent of the entire consumption is used for engineering con- sumption. While accurate figures are of no particular value, it is interesting to know that the timber used annually in en- gineering construction has an estimated valuation of fully $100,000,000. The per eapita consumption in the United States has always been higher than in most other countries — about .500 hoard feet per capita in 190.5 — because of the liberal use of the most widely available building material. As wood is used more wisely, its life will increase, and as more timber is ere- osoted or given other preservative treatment, the annual renew- als for any class of structure will naturally decline. On the other hand, educational propaganda and the application of standard and permanent timber construction by the engineer- ing profession, will tend to increase or at least maintain the present lumber consumption for perhaps a decade. Follow- ing this, since renewals will be reduced by a more proper use of timber, there will be a falling off in consumption, the demand then being for new structures and for the reduced volume of renewals. To the structural engineer the possibil- ities in this line are very great . Quoting again from Messrs. Greeley and Betts: "The country is thus evidently drawing upon its forest capital at the rate of 60 to 70 billion feet annually (including the loss by tire and insects). Long before the present enormous forest resources are eaten up, however. it is more than probable that readjusting eeonomic conditions, particularly higher values for timber and a lower per capita consumption, will reduce the annual drain to an amount not more than the annual growth." Page nine TIMBER FOR Relative '^ le l yrict °* l umuer * las fluctuated in accordance Cost w ^h ti*adc and economic condition* in much the same degree as other materials. A comparison between certain species in an abnormal year, such as 1895, with a year of marked business activity as in 1905, might show a difference of as much as one hundred per cent. An analysis of prices shows, however, that averaging years of depression with periods of active demand, lumber follows as nearly a normal curve as most other materials. The following tabulation, compiled from the Report by the Census Bureau and Forest Service of the average price per thousand feet at the sawmills of the principal kinds of lumber from 1899 to 1912, shows clearly the course in lumber prices during this period. Average Mill Prices of Principal Kinds of Lumber. Kind of Wood i'.»l -» li'll l'.HO ,.,,,.. 190> iuo; 1«J06 1904 1899 All kin. Is $1535 $15.05 $15.30 $15.38 $15.37 $16.56 $16.54 $12.76 $11.13 "i ill<>\\ pine .... L4.3I Douglas fir 1 1.5* White pine 19.13 Hemlock 13.68 \\ «-i.r?i pine . . . 13.62 Spruce 1 7.o:j Cypress 20.09 Redwood 14. 13 I edar 14.4:. Larch 1 1.96 White fir 9.*6 Tamarack (1) Sugar pin*' ..... 1 1 1 Balsam tir x i) Lodgepole pine . . l > Dak 19.6 Maple 15.56 Yellow poplar. . . 24.06 Red gum 12.60 ( hestnut 16.62 SOFTWOODS. 13.87 13.29 12.69 12.66 14.02 15.02 9.96 8.46 11.05 13.09 12.44 11.97 14.12 14.2(1 9.51 8.67 18.54 18.93 1*.16 1*.17 19.41 18.32 14.93 12.69 13.59 13.85 13.95 13.65 15.53 15.31 11.91 9.98 13.88 l 1.26 15.39 15.03 15.67 14.ol 11.30 9.70 16.14 16.62 L6.91 16.25 17.26 17.33 14.03 1 1.27 20.54 20.:. l 20.46 21.30 go i •> 2 1 .94 17.50 13.32 13.99 1 5 . 5 2 14.80 15.66 17.70 H 4 12.83 10.12 13.86 1 5.5". 19.95 18.03 19.14 18.12 14.35 10.91 11>7 11.85 12.39 1 1.81 13.07 1 1 .9 1 *.94 8.00 10.64 11.5 2 13.10 11.38 15.45 12.91 (1) <D ( 1 1 13.30 13.18 12.86 15.71 15.63 12.42 12.48 i ; . 5 2 18.68 J*. 14 17.78 19.84 16.11 (1) 12.30 13.42 14.4* 13.99 14.36 16.16 (1) (1) (1) 12.41 14.*- 16.25 H» Hi Hi ID (1) HARDWOODS. 19.14 18.76 20.50 21.23 2 1.2: J 21.76 17.51 13.78 15.49 16.16 1 ■>., i L6.30 16.84 15.53 14.94 11.S3 Z 5.4( ; 24. ri 25.39 - - * * • » ' 1 24.91 2 4.21 18.09 14.03 12.11 12.26 13.20 13.08 14. 10 13.46 10.87 9.63 16.63 1 16.12 16.27 17.04 17.49 1 '* 13.37 Page ten STRUCTURAL PURPOSES HARDWOODS — (Continued) Birch 17.43 1(3.61 17.37 16.95 16.42 17.37 17.24 Beech 13.51 14.09 14.34 13.25 13.50 14.30 14.05 Basswood 19.26 19.20 20.94 19.50 20.50 20.03 18.66 Hickory 23.29 22.47 26.55 30.80 29.66 29.50 30.42 Elm 16.87 17.13 18.67 17.52 18.40 18.45 18.0S Ash 20.27 21.21 22.47 24.44 25.51 25.01 24.35 Cottonwood 20.44 18.12 17.7S 18.05 17.76 18.42 17.15 Tupelo 13.61 12.46 12.14 11.87 13.36 14.48 14.13 Sycamore (1) 13.16 11.10 14.77 14.67 14.58 (1) Walnut (1) 31.70 34.91 42.79 42.53 43.31 42.25 15.44 12.50 (1) (1) 16.86 12.84 :J3.94 18.78 14.45 11.47 18.77 15.84 14.92 10.37 (1) (1) (1) 11.04 45.04 36.49 (1) Not reported separately. The values are not intended to cover all grades of lumber nor to indicate market prices in all localities. They are how- ever, a correct basis for comparison of values at the sawmill, and show that there has been no undue advance in lumber prices, nor one out of proportion to the general rise in com- modity prices during the same period. The statement that lumber has reached such an exorbitant price that it can no longer be used, is best met by the records of the United States Bureau of Labor Statistics, the authority on the wholesale prices of all commodities. On page 266 of Bul- letin 181 of the Bureau is given a table of the relative prices of nine groups of commodities from 1860 to 1914, the average price from 1890 to 1899 being taken as 100. The chart on page 12 shows in graphic form the record of the Bureau for three of the most important groups of commodities; farm products, food, and lumber and building materials. On the chart, farm products are indicated by a dotted line, food by a line of dashes, and lumber and building materials by a solid line. A single glance at the chart completely answers the pop- ular statements as to undue advances in lumber prices. On an average, these prices have run between those of farm product^ and of food for the last fifty years, and with neither as high points nor as low points as the two other groups. Still further, it will be noted that the prices of lumber and building materials are relatively lower now than they were forty years ago: yet at « Vane eleven TIMBER FOB FARM PRODUCTS FOOD £7C- --LUMBER AND BU/LD/NC MATERIALS \ that time no one thought that lumber was too expensive to build with. The price of lumber at the end of 11)14 was lower than at any time since 1900, and even with the increase in prices which occurred the latter part of 1915, was on January 1, 1916, still less than in 1912. ern Mod Structural Modern structures impose Aery strict require- ments on the material used. It is for the struc- Requirements tural engineer rather than for the consumer to determine what material is best in particular locations. This selection is further determined bv city build- ing codes, by the need for safety from fire, and the necessity for permanence in congested city districts. Pane tivelve STRUCTURAL PURPOSES It is a logical development that structural timber should not be used in sky-scraper districts. The question of wooden floors, doors, inside trim, and fire-resistant construction is a problem for the engineer. There is ample evidence that the tendency in many cases has been to go too far in the elimination of wood, since its modern nse for these purposes is not the con- tributing cause of tire. At any rate, the character of the eon- tents is the underlying conflagration hazard in many cases, as evidenced by the burning out of the central districts of cities such as Baltimore and San Francisco. For factory and warehouse purposes, suburban and country dwellings, and in many other situations, wood may safely pre- dominate, and if properly used meets all requirements. With the basic facts of availability and economy established and data available as to strength and durability, the engineer can readily specify the extent to which structural timber may be safely used to the advantage of the owner or community. Permanence Permanence as applied to construction is a anc l relative term, since outside of definitely Depreciation planned and congested city districts perma- nence may mean a building lasting ten years or fifty years, according to the conditions. Both com- mercial buildings and dwellings serve their original purpose only while community or industrial conditions make their occu- pancy attractive or profitable. The growth of nearly all Ameri of residential streets to factory or warehouse districts, with no way of anticipating ultimate developments. The capitol at Washington, for in- stance does not face the main part of the city, because it did not grow in the direction which was anticipated. The lack of stability in city development does not mean that strictly temporary, unsafe, or unsightly structures should be built, but it does indicate definite advantages in the use of timber as the main structural material in dwellings and com- Page thirteen TIMBER FOR mercial buildings of moderate size and cost Many mill con- structed buildings in New England are practically as good today as when built a hundred years ago; while frame dwell- ings will last for generations, as evidenced by colonial homes which are still sound and comfortable after more than a cen- tury of use. The main point is that whether used for perma- nent or temporary purposes, timber structures may be removed or changed more readily, and may be adapted and remodeled more economically than if built of materials which in them- selves are claimed to be more permanent. The question of depreciation in buildings of all kinds is very important. So many factors must be considered that deprecia- tion on any type of building — wood or other material cannot be fixed on any absolute rule or percentage, nor in an arbitrary manner. Service records on wooden, brick and stone buildings run back through many years, and establish a basis for average depreciation figures. Some of the newer building materials, however, as well as some of the newer types or designs in struc- tures, have not been given this test of time. In buildings of the standard mill construction type depreciation is commonly estimated at from 1 to 1 ' . per cent annually. This, of course, is based upon well designed buildings, properly constructed of good materials. Comparative depreciation charges between different types of buildings will be more or less arbitrary, no mattei' how carefully compiled, because they depend not onl\ on the actual life of the building and on the character of th< occupancy, but on the indefinite period of usefulness, regard- less of the material. Taking into consideration several prin- cipal factors, such as community changes, expansion of city growth, developments in architectural types, and bousing re- quirements, a thirty to forty year period is a fair estimate of the term of usefulness of anv kind of structure. In view of this, well designed and properly built timber structures will in many cases meet all requirements of occupancy and use. and prove verv economical, both in first cost, and in ultimate altera- tions or removal. J'<i_< fourii STRUCTURAL PURPOSES Fire A stick of timber will burn and so will a wood, a Hazard . brick, a concrete, a steel or a terra cotta building. Buildings burn, not because of the materials of which they are built, but on account of faulty construction, lack of tire precautions, hazardous contents and carelessness. Tbe enormous annual fire losses in the United States very properly constitute a subject of national concern and every possible measure should be taken for their reduction. But that the general use of wood in the ordinary types of structure is the basic cause of tires is not a reasonable assumption. To condemn wood in any form and to advocate tin* use <>1 noncombustible building material has been the aim of several publicity campaigns. The American people are too sane to b< led into a frenzv of condemnation against a material which has • sheltered and sen ed them from time immemorial, and a rtainly engineers and architects will continue l<> seled building mate- rial on its merits. The first consideration in the usi of timber is that it should never he placed in a structure where undent nt- ing experience has not shown it to be reasonably safe. On th other hand, its elimination because of the \\id -spread slogan thai "wood burns," and in favor of more expensive, less adapt- able and less beautiful materials which have no1 stood th serv- ice test of time, is as unreasonable as to drink wine instead of water because the latter may contain disease !M rms. There is _, statistics. One of the greatest fallacies is that of drawing conclusions regarding fire losses from per capita data. To say that the annual fire loss in the United States is $2.50 per capita against 58-cent per capita loss in Europe is to ignon i necessarj meas- ure oi' value. The fact that the United States has about three and one-half times the number of tires and also \er\ nearly three times the number of buildings, leads to the simple con- clusion that Europe has fewer fires because it has fewer build- ings. Not onlv do we have nearly thr times th< number of buildinus but substantially twenty-five percent le>s population. These figures are gleaned from the Underwrite! report tor Poi *n TIMBER FOB the year 1913. It develops from this same source of informa- tion that the average loss per fire in the United States was $532, while the average in European cities was $8*2 greater or ^614. From this it is apparent that the average building in the United States is a fourteen per cent better fire risk than the average building in European cities. The whole fire question with respect to timber construction largely resolves itself into the fact that the public has been told about the fires in wooden buildings, while little or nothing has been said about what actually happens to buildings of so-called non-combustible material. Fire prevention propaganda, based on proper construction, adequate safeguards, elimination of hazardous contents and carelessness, and the use of automatic sprinklers, will be welcomed by the Lumbermen and go farther towards actual reduction of losses than an attempt to create prejudice against wood. A great many reports on fire prevention and the use of structural materials in building, state that a carefully designed timber structure is as safe against fire as any other type of structure if all floors are isolated, elevators and stairways en- * closed in fireproof shafts with all openings protected by self- closing doors, and proper sprinkler systems used throughout. A heavy timber which has been charred bv fire becomes of slow-burning nature due to the charred coating, in the same manner that a solid Jog burns slowly. Even when chaired. th< timber loses but Little of its original strength, and the building is not distorted nor weakened perceptibly. Mill Mill construction is a type of structure which Construction has been well known to enmn<< is for manv years. Its advantages as an economical and substantia] form of building for warehouses, factories, and many other uses are as strong today as ever, if properly d< signed with well-selected structural timber. Ileavv mill cmi- ft struct ion with a sprinkler system is a very acceptable fire risk, is evidence d bv its being pre! rred o\ er .ill other risks bv st rone Pol n STRUCTURAL PURPOSES mutual fire companies in New England. In this same territory it is stated in "Engineering of Shops and Factories" by II. G. Tyrrell, C, E., that there are more wood-framed mills than all others combined. A bulletin is under preparation which discusses the details of standard mill construction from the standpoint of the struc- tural engineer. Dwellings The frame dwelling is our commonest type. It is cheap, beautiful if properly designed, permanent if built of well-selected timber, and fully meets all of the re- * quirements of the home builder and real estate owner. Manx of the possibilities and advantages of the moderate priced frame home have been ignored or overlooked because no archi- tectural skill or training was utilized in the design or construc- tion. Model plans are available from many sources, and while they are of great assistance to the man who cannot afford to consult an architect, it would be economy in the long run if such buildings, especially of the more pretentious type, could be constructed under the supervision of competent architects. A point frequently overlooked in considering other than frame construction for the dwelling is the relative heat radia- j-> Hon in walls of various kinds. In tests made bv the German * Government of heat transmitted per square foot of wall sur- face per hour, it was found that the frame house, with 7/l<> inch clap-boards, building paper, sheathing, lath and plaster, had a heat loss factor of .2.*J of a H. T. I \ per degree as against .37 for plain brick walls one brick thick, and .36 for brick walls one brick thick plastered inside.* In stone walls a thickness of 20 inches is required with sand stone to reduce the heat fac- tor even to ..'3.5, while with a 12-inch stone wall the loss was .4,5. Concrete blocks are in about the same class as limestone in coldness and will have a heat loss factor of about 35 to 50 per cent more than frame construction. lor further details reference i> made to ;i publication mi ln-;itin- and ventilating issued by the Buffalo Ford Company of Buffalo, X. V.: also t<> the book on "Heating and Ventilating BuiMinu-.'' by Carix-ntcr. Pane seventeen TIMBER FOR With the public at present somewhat influenced by the bug- aboo that "wood burns" many prospective builders attempt to use non-combustible materials. Here again amateur effort is not likely to bring gratifying results, and if the architect is called in the builder will have an opportunity to learn the actual relative merits and fire hazard of different types of dwellings. Even if the factors of beauty and economy can be taken care of in the home built of other than frame construc- tion there remains the fundamental cause of fire, which is in no wav influenced by the character of the structure. The elim- • * ination of individual carelessness is the first essential, after which the severity and frequency of the dwelling house fire is determined by the character of the contents. The frame dwelling has advantages of warmth, low cost, beauty and comfort which no other type can equal. All the sentiment of home centers around the "homey" character of the wood of which it is built. The treasures of the home will burn ;:s quickly and completely within non-combustible vails as in a frame of wood. To banish the fire hazard, we should build tor safety by cutting off vertical openings, put smooth fire- clay Linings in chimneys, and if the home is not isolated from neighboring dwellings, use a fire-retardent preparation on the wooden shingles and a fire-resistant paint on the side walls. Then eliminate individual carelessness, take proper precautions always, and the home and all it means will be safe. pj re A developmenl which increases the adaptability Retardents °* UO(, d for many purposes, is along the line of fire retardents. Processes and materials have been perfected which are eminently practical. They are in most e;«M s a paint or chemical, which can be applied with a brush or by an immersion process. A special bulletin on tins subject is in preparation and for the present it is sufficient 1«» say that there are now <>n the market fire retardents which are esp< dally adapted to shingles, and will render them p< Eminently fin resistant in eater measure than many of the so-called iii< j - 1' e hfrt STRUCTURAL PURPOSES proof roofings. Some of these same materials may be applied to other portions of the structure where it is desired to reduce the fire hazard. The same influences which have created a prejudice against the use of structural timber in commercial structures and franu dwellings have attempted to eliminate the ghingle roof. Tht propaganda is based entirely on I he fire hazard rince it is well known that good shingles, properly laid with good nails, will give better service than any other form of roofing material, and in case of fire in adjacent buildings can be met down so as to constitute an excellent lire break. No one denies that a dry shingle roof, particularly an old one, will ignite from brands and large sparks, nor does an\ sane man, lumberman or otherwise, advocate other than non-combustible roofs in con- gested city districts or wherever there is real danger. Hut it i> equally certain that many other roofing materials arc m the same class with shingles as regards inflammability, and when buildings are separated as in small towns and residential dis tries, the wooden shingle has qualities of beauty, economj storm resistance, and long life superior to any other roof covering. Wood With the advance in engineering knowledge Preservation there have come important developments in the preservative treatment of structural timber against decay. Treating processes have been applied on commercial seale in Europe for over a < ntury. and m this country for some forty years. The most extensive ao pt- ance of this practice has been by the railroads for treatment of cross-ties and structural timbers. bridg. trestles, dock etc. It is entirely feasible, however, to apply the same methods to the treatment* of structural timbers in many typ f build- ings, and the possibilities along this line have been lar. ly overlooked. St 1 is painted to prevent rust, eonerete is coated to prevent abrasion and to add waterproofing qualities, so it i Page nineteen TIMBER FOR STRUCTURAL PURPOSES entirely reasonable and in no way a reflection on the stability of timber that under certain conditions it should be treated with creosote, or some other preservative, to prevent decay. The inside timbers in many buildings where exposed to moisture should be treated with creosote. All timber in con- tact with the ground may be preserved indefinitely against de- cay. Mud sills and beams on foundations, basement planking, stringers, and other structural parts may be creosoted to secure permanence and stability. This not only reduces renewals to a minimum but establishes a constant factor of safety, since there is no reduction in strength from decay. Such timbers if given an empty cell treatment and left exposed to the air before being put in place will have no objectionable odor. In situa- tions where the color or use of creosote for any reason would be objectionable zinc-chloride may be used. The intelligent use of wood-preserving methods has the further advantage that the factor of durability in structural timber can be largely ignored and consideration given only to strength requirements. Many timbers which are naturally non- durable are cheaper than the more durable woods, thus effect- ing in the first cost a saving which largely covers the expense of treatment. Summary In this introductory publication an attempt has been made to review briefly the many engineering phases connected with the use of structural timber in mod- ern construction. The general announcement that the lumber manufacturers have under preparation a series of tech- nical bulletins dealing with timber and wood products in all forms, should be welcomed by all architects, engineers and builders. Their libraries have contained reference books on practically all building materials except wood, and this lack will now be supplied with the best engineering data on struc- tural timber and wood construction. These bulletins will be made readily available to all who are interested. Page twenty '